A 28-year-old woman complains of fatigue and a sense of fullness at the base of her neck. She has no significant past medical history, gave birth to a healthy infant 4 months ago, and is only taking oral contraceptives. On examination, vital signs show pulse 88, blood pressure 110/66, temperature 37°C (98.6°F), and respirations 12. Her thyroid gland is homogeneously enlarged, and she has a very mild tremor of the outstretched hands. The rest of the examination is normal. Laboratory evaluation reveals the following:
What is the most likely diagnosis?a. Thyrotoxicosis factitia
The patient’s clinical presentation is most consistent with postpartum thyroiditis, a form of autoimmune-induced thyrotoxicosis that occurs 3 to 6 months after delivery. The hyperthyroid state usually lasts for 1 to 3 months and is generally followed by a hypothyroid state of limited duration. The patient’s thyroid gland would not be enlarged if she were taking exogenous thyroid medications. Subacute thyroiditis usually presents with a tender, enlarged thyroid gland. The patient’s thyroid gland is described as homogeneous, not nodular, which would be inconsistent with toxic multinodular goiter. Struma ovarii is unlikely because of the enlargement of the thyroid gland. Struma ovarii is the name given to the approximately 3% of ovarian dermoid tumors or teratomas that contain thyroid tissue. This tissue may autonomously secrete thyroid hormone. Postpartum thyroiditis can be distinguished from Graves disease with thyroid uptake scan; uptake will be suppressed in thyroiditis but normal to increased in Graves disease.